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The present study has the intent to analyse the contribution of navigational strategies and gender in the delayed recall of a learned path on a map. For this purpose, we first evaluated the different navigational strategies through a battery of specific tests; 51 participants were instructed to study a schematic map of a route in a city map­view for 220 seconds. Then, they were divided into three groups based on their navigational strategies: landmark users, route users, and survey users. After 5 minutes, during which they provided anamnestic information, they were asked to recall the learned path and to draw it on a silent map. Correct positions and false recognitions were evaluated. Results showed that the differences in performance were due to the navigational strategy and not to gender. Individuals using the survey strategy, which is more complex and efficient, are more accurate and have fewer false memories than individuals that use a landmark one, the poorest strategy from a navigational point of view. The absence of differences associated with gender corroborates previous findings that emerge from the Aeronautic literature: men and women with the same abilities perform cognitive tasks with the same efficiency. [ABSTRACT FROM AUTHOR]

Background: Most SARS-CoV-2 rapid antigen detection tests (RADTs) validation studies have been performed on specimens from COVID-19 patients and negative controls or from mostly symptomatic individuals. Herein we evaluated the diagnostic accuracy of AFIAS COVID-19 Ag, hereinafter denominated as AFIAS, during a COVID-19 screening program surveillance testing conducted among personnel of an Italian military airport. Methods: Nasopharyngeal swabs (NPSs) were collected from study participants and were analysed by both AFIAS and RT-PCR assay. A questionnaire collecting demographic and exposure data were administered to all participants. AFIAS accuracy parameters including Cohen's kappa (K) were determined. Results: Overall, from November 2020 to April 2021, 1294 (NPSs) were collected from 1183 participants (88.6% males, 11.4% females; mean age were 41.3, median age 42). Forty-nine NPSs (3.78%) were positive by RT-PCR, while 54 NPSs were positive by AFIAS. Overall baseline sensitivity, specificity, positive and negative predictive values were 0.633, 0.981, 0.574, 0.985, respectively and K was 0.585 (moderate). AFIAS sensitivity tended to be higher for NPSs with higher viral load. A higher sensitivity (0.944) compared to the overall baseline sensitivity (0.633) was also found for NPSs from participants with COVID-19 compatible symptoms, for which K was 0.891 (almost perfect). Instead, AFIAS sensitivity was quite poor for NPSs from asymptomatic participants. Most false negative NPSs in this group had moderate viral load. Conclusion: Overall, AFIAS showed high specificity but only moderate sensitivity, mainly because of the high proportion of asymptomatic participants. However, AFIAS showed good sensitivity for NPSs with high viral load and nearly optimal accuracy parameters for NPSs from participants with COVID-19 compatible symptoms. Thus, taking into consideration its performance features, this test can be useful for COVID-19 case identification and management as well as for infection control. [ABSTRACT FROM AUTHOR]

Moral sense is defined as a feeling of fairness or unfairness of an action that knowingly causes harm to people other than the subject. It is crucial in determining human behavior and becomes pivotal in operational environments. Here we assessed whether professional daily life experience in an operational environment affects moral judgment by asking 41 military pilots of the Italian Air Force (P) and 69 controls (C) to solve 40 moral dilemmas. We found that P gave more morally acceptable utilitarian responses to moral dilemmas. Interestingly, men and women in P equally accepted utilitarian resolutions of moral dilemmas, whereas in C women were less prone than men to accept utilitarian responses. We conclude that professional daily life experience of P, in an operational environment, affects moral judgment and mitigates gender predisposition towards moral dilemmas. [ABSTRACT FROM AUTHOR]

Background: It is well known that cognitive and emotional changes occur during pregnancy, but little is known about their magnitude or their time of occurrence and recovery. During pregnancy memory is one of the most impaired cognitive functions. Although long-term aspects of memory have been investigated, other aspects of memory have not yet been explored (i.e., navigational memory and reaching memory). Case presentation: Here we describe the changes in reaching and walking memory that occurred during pregnancy and one year after delivery in an Italian female military pilot (Case 1) with high spatial ability. In memory tests she showed a classical dissociation between performance in reaching and walking distance, which indicated a failure of working memory, learning, and storage in reaching space. This suggests that her expertise served as a protective factor mitigating her low walking memory performance, and saving the topographical component. We compared her performance with that of two non-pregnant control groups (i.e., women pilots and non-pilots) and found that Case 1’s reaching memory performance was significantly worse than that of the control groups. Even one year postpartum, Case 1’s performance was not yet the same as that of the other pilots. Conclusions: These findings contribute to our knowledge of the specific, as yet unexplored, aspects of memory deficits in women pilots during pregnancy and postpartum and suggest the need for better neuropsychological assessment before these women return to work in operational environments. [ABSTRACT FROM AUTHOR]

Prism adaptation (PA) is a well-known and widely used technique for rehabilitating unilateral spatial neglect and studying sensory–motor plasticity. However, there is conflicting evidence in the literature regarding its effectiveness which may arise from differences in the type of prisms used, clinical characteristics of the patients, and the procedure used in training. Individual differences may play a role in PA effectiveness in rehabilitating neglect, affecting both its development and its effects. Field-dependent/independent cognitive style is a pervasive characteristic of individual functioning, affecting how environmental information is processed. Here, we tested the hypothesis that cognitive style plays a role in PA efficacy by submitting to a protocol of prism adaptation to 38 health participants, who were classified as field-dependent (FD, N = 19) or field-independent (FI, N = 19), by using the Embedded Figure Test. Results show that during the exposure phase, FI individuals needed a lesser number of pointing movements to reduce the deviation error than FD individuals. However, there are no differences in the extinction of sensory–motor and cognitive after-effects. These results suggest that prismatic adaptation is affected by individuals' cognitive style since FI individuals will need fewer trials to reach adaptation and this could explain why using this rehabilitation technique with a unique, standard protocol is not always effective. [ABSTRACT FROM AUTHOR]

A noninvasive approach in the delivery room in place of intubation and mechanical ventilation can reduce rates of bronchopulmonary dysplasia and death. Nevertheless, the rate of nasal continuous positive airway pressure failure still remains high. In order to prevent lung injury and to enhance the success of continuous positive airway pressure, sustained inflation (administration by face mask or nasopharyngeal tube of a high peak pressure of 20-25 cm H2O, maintained for 10-15 s) has been recently proposed to establish an early and efficient functional residual capacity in the delivery room. Sustained inflation is an intriguing therapy, although the results of clinical trials are controversial in terms of respiratory outcomes. A critical role in the success of sustained inflation could be the presence of open or closed glottis and the contribution of spontaneous breathing that allows air to enter the lungs during the maneuver. Recent neonatal resuscitation guidelines suggest that sustained inflation may be considered in individual clinical circumstances or research settings. Respiratory distress syndrome (RDS) is the most common respiratory pathology in preterm infants and bronchopulmonary dysplasia (BPD) remains an important sequela in these patients. In the past, conventional mechanical ventilation or high-frequency oscillatory ventilation plus surfactant replacement therapy have been considered the standard approach for management of RDS. However, we know that lung injury is directly related to duration of mechanical ventilation and therefore noninvasive approaches [e.g. nasal continuous positive airway pressure (CPAP)] often associated with surfactant administration have been demonstrated to be a valid alternative [1]. Two recent meta-analyses suggest that a noninvasive approach from the delivery room instead of intubation and mechanical ventilation can reduce rates of BPD and death with a number needed to treat of 35 and 25, respectively, in very preterm infants [2, 3]. Nevertheless, the rate of CPAP failure remains high. In fact, recent randomized controlled trials (RCTs) reported that more than 50% of very low birth weight infants initially assisted in the delivery room with nasal CPAP required mechanical ventilation in the neonatal intensive care unit [4-6]. [ABSTRACT FROM AUTHOR]

This paper proposes a general approach for voltage-quality regulation. The same framework covers voltage-amplitude variations, dips, and swells. The framework uses the difference between power-quality events and power-quality variations to introduce a "responsibility-sharing curve" distinguishing between normal operational voltage for which equipment should be immune and events that are subject to voltage-quality regulation. It is further proposed to use equipment immunity requirements as a basis for the responsibility-sharing curve. [ABSTRACT FROM AUTHOR]

Background: Military pilots show advanced visuospatial skills. Previous studies demonstrate that they are better at mentally rotating a target, taking different perspectives, estimating distances and planning travel and have a topographic memory. Here, we compared navigational cognitive styles between military pilots and people without flight experience. Pilots were expected to be more survey-style users than nonpilots, showing more advanced navigational strategies. Method: A total of 106 military jet pilots from the Italian Air Force and 92 nonpilots from the general population matched for education with the pilots were enrolled to investigate group differences in navigational styles. The participants were asked to perform a reduced version of the Spatial Cognitive Style Test (SCST), consisting of six tasks that allow us to distinguish individuals in terms of landmark (people orient themselves by using a figurative memory for environmental objects), route (people use an egocentric representation of the space) and survey (people have a map-like representation of the space) user styles. Results: In line with our hypothesis, military pilots mainly adopt the survey style, whereas nonpilots mainly adopt the route style. In addition, pilots outperformed nonpilots in both the 3D Rotation Task and Map Description Task. Conclusions: Military flight expertise influences some aspects of spatial ability, leading to enhanced human navigation. However, it must be considered that they are a population whose navigational skills were already high at the time of selection at the academy before formal training began. [ABSTRACT FROM AUTHOR]

Background: Endogenous ovarian hormones as well as exogenous oestradiol and progesterone play an important role in cognitive processing. Specifically, these hormones play a role in different aspects of memory, both in terms of storage capacity and temporal duration of the mnemonic track. These hormones also have various effects on different types of memory (i.e., verbal, visuo-spatial, prospective). This study investigated the effects of hormones on topographic memory, a type of memory specifically needed to recall a pathway and to acquire spatial information about locations, distances, and directions.Methods: We compared 25 naturally cycling women (NCW) in two different cycling phases, the early follicular phase (4th - 5th days) and the mid-luteal phase (20th-21st days), with 26 women taking oral contraceptives (OC) tested in the active pill phase (20th to 21st day of OC cycle) and the inactive pill phase (2nd to 4th day of OC cycle). Both groups performed the Walking Corsi Test to assess topographic memory in their respective cycling phases. Women were instructed to learn an eight-step sequence path and recall the path five minutes later.Results: We found that the two groups differed in terms of learning the 8-step sequence path; OC users were always better (4-5 days vs. 20-21 days) than NCW. No differences emerged in the delayed recall of the same path.Conclusions: As already observed in other memory domains (i.e., verbal memory, emotional memory), OC users showed an advantage in terms of topographic learning. Our results might be explained by hormonal mechanisms and may suggest the future application of OC in women with topographic disorders or visuo-spatial difficulties. [ABSTRACT FROM AUTHOR]

Background: A sustained inflation (SI) at birth in preterm babies may be ineffective unless the infants breathe. Gain in lung volume is associated with breathing during delivery room non-invasive management. Objective: To describe the breathing patterns of preterm infants during an SI and correlate to a calculated gain in lung volume. Methods: Retrospective observational study. Data collected from a respiratory function monitor during SI (25 cmH2O for 15 s then PEEP at 5 cmH2O) through a face mask in preterm infants (gestational age [GA] ≤ 31 weeks). Spontaneous breaths, inspiratory time (TI), inspiratory/expiratory tidal volume (Vti/Vte), and gain in lung volume were determined. Results: 30 SIs in 20 infants (mean GA 27 weeks; birth weight 825 g) were analysed and stratified in 2 groups according to spontaneous breathing: SIs without spontaneous breaths (apnoea: n = 11) and SIs with spontaneous breaths (breathing: n = 19). Mean GA was lower in the apnoea group versus the breathing group (25 vs. 27+5 weeks; p = 0.01). Mean birth weight was lower in the apnoea group versus the breathing group (683 vs. 860 g; p = ns). In the breathing group, the mean number of spontaneous breaths was 4 with a mean TI of 0.52 min, the mean Vti/kg was 5.9 mL/kg, and the mean Vt e was 2.7 mL/kg. The calculated mean gain in lung volume was 7.5 mL/kg in the apnoea group and 17.8 mL/kg in the breathing group (p = 0.039). Conclusions: Actively breathing infants during an SI at birth showed a gain in lung volume higher than apnoeic infants. Spontaneous breathing during SI seems to be related to GA. [ABSTRACT FROM AUTHOR]

The Developmental Topographical Disorientation (DTD) is a pathological condition that impairs an individual's ability to orient in space, even in the most familiar environments. It is a lifelong selective condition in individuals without brain damage or without impaired general cognitive functions. Here, we aimed at characterizing 54 individuals with DTD identified in a previous study, aged between 18 and 35 years and assessed through a 4-year-long online survey. To this purpose, we compared them with 54 matched healthy participants. We described the demographics, sense of direction, town knowledge, navigational strategies, left-right confusion as well as agnosic disorders (for landmarks, faces and objects). This novel study attempts to characterize the phenotype of DTD, providing an important contribution to the worldwide definition of a condition that was first described only 13 years ago, but which, considering the growing number of cases complaining of the disorder, deserves continuous and increasing attention. [ABSTRACT FROM AUTHOR]

In the last decade, several cases affected by Developmental Topographical Disorientation (DTD) have been described. DTD consists of a neurodevelopmental disorder affecting the ability to orient in the environment despite well-preserved cognitive functions, and in the absence of a brain lesion or other neurological or psychiatric conditions. Described cases showed different impairments in navigational skills ranging from topographic memory deficits to landmark agnosia. All cases lacked a mental representation of the environment that would allow them to use high-order spatial orientation strategies. In addition to the single case studies, a group study performed in Canada showed that the disorder is more widespread than imagined. The present work intends to investigate the occurrence of the disorder in 1,698 young Italian participants. The sample is deliberately composed of individuals aged between 18 and 35 years to exclude people who could manifest the loss of the ability to navigate as a result of an onset of cognitive decline. The sample was collected between 2016 and 2019 using the Qualtrics platform, by which the Familiarity and Spatial Cognitive Style Scale and anamnestic interview were administered. The data showed that the disorder is present in 3% of the sample and that the sense of direction is closely related to town knowledge, navigational strategies adopted, and gender. In general, males use more complex navigational strategies than females, although DTD is more prevalent in males than in females, in line with the already described cases. Finally, the paper discusses which protective factors can reduce DTD onset and which intervention measures should be implemented to prevent the spread of navigational disorders, which severely impact individuals' autonomy and social relationships. [ABSTRACT FROM AUTHOR]

Many automotive industries are developing technologies to assist human drivers in suggesting wiser choices to improve drivers' behaviour. The technology that makes use of this modality is defined as a "digital nudge". An example of a digital nudge is the GPS that is installed on smartphones. Some studies have demonstrated that the use of GPS negatively affects environmental learning because of the transformation of some spatial skills. The main purpose of this study was to investigate the use of the GPS nudge and its relationship with spatial ability, together with its function in supporting the driving behaviour of non-expert drivers, in order to reduce the number of road crashes. A total of 88 non-expert drivers (M age = 21 years) filled in questionnaires and carried out tasks to measure spatial abilities, sense of direction, driver behaviour, and six different real-life driving scenarios. The results reveal that the higher the spatial skills are, the greater the GPS use is, and that drivers who use GPS improve their sense of direction. Moreover, people with high visuospatial abilities use GPS more extensively. Finally, young drivers do not consider the GPS aid to be useful when they have no time pressure. The results are discussed by taking into account the familiarity-and-spatial-ability model. [ABSTRACT FROM AUTHOR]

Purpose: To investigate possible renal damage in healthy men exposed to extreme hypobaric hypoxia, using urinary Neutrophil Gelatinase-Associated Lipocalin (NGAL) concentration as biomarker. The value of NGAL as a biomarker of proximal tubular cell damage under hypoxic conditions was also tested in vitro experiments. Methods: NGAL was assayed in a cohort of air cadets (n = 16) exposed to hypobaric hypoxia in a hypobaric chamber during their training program. In all subjects, urine creatinine (Cr) and urinary NGAL levels were measured immediately before, 3, and 24 h after hypobaric environment exposure. Three in vitro experiments using proximal tubular cell cultures were also performed to measure NGAL gene expression, NGAL secretion in the culture medium and to evaluate apoptosis under two cycles of hypoxia and reoxygenation. Results: In the in vivo study, geometric means of urinary NGAL/Cr ratio measured 24 h after hypobaric hypoxia in the hypobaric chamber were significantly lower than baseline values (13.4 vs 25.9 ng/mg, p = 0.01). In cell cultures, hypoxia down-regulated NGAL gene expression without significantly changing NGAL secretion in the culture medium. Hypoxia significantly increased the percentage of apoptotic/necrotic cells, especially after the second hypoxia-reoxygenation cycle. Conclusions: Exposure to hypobaric-hypoxic environments does not cause significant and irreversible renal tubular injury in vivo and in vitro, except than in a late stage. The hypoxic insult does not seem to be mirrored by an increase of urinary NGAL in healthy men nor of NGAL gene expression in HK-2 cell culture or secretion in the culture medium in the in vitro conditions reported in the present study. [ABSTRACT FROM AUTHOR]

Electrical energy planning of modern electric power system requires great attention for the air pollution problem. This is in accordance to the increasing tendency to optimise the production processes in the respect of their sustainability. Moreover, the advent of the deregulation in the electric energy market has involved substantial modifications of philosophy in planning and managing the electrical power system. These aspects together offer new challenge in defining proper system study methodologies and suitable planning strategies. One of the most complex problems in the planning strategies is the data management uncertainty related to load forecasting and environmental modelling. In this paper a robust optimal planning procedure is formalized, taking adequately into account the problem of stochastic variables presence, allowing to satisfy the air quality and load demand forecast constraints in spite of uncertainties. The proposed approach addresses generation planning, where the various aspects have been integrated to solve the problem in a feasible and realistic way. A numerical application to an electrical power system with respect to a regional area is reported in the final part of the paper, showing the applicability of the proposed methodology. [ABSTRACT FROM AUTHOR]

We investigated whether the gender differences in working memory are linked to the nature of the stimuli (verbal vs. visuo-spatial) or to the type of processing (active vs. passive). With this aim, we administered two well-known tests: Corsi Block-tapping test (CBT) and the Digit span (DS) using two versions: forward (fCBT and fDS) and backward (bCBT and bDS). During the forward processing (fCBT and fDS), subjects being required to repeat stimuli in the same order they are presented, passive working memory is assessed. Otherwise, during the backward processing (bCBT and bDS), subjects being required repeating stimuli in an order opposite to that of presentation, active working memory is assessed. A total of 208 college students (104 women) were assessed. We found a gender effect on fCBT and bCBT, but not on fDS and bDS, with men outperforming women. The results from the present study support previous findings in which the presence of gender differences emerged in visuo-spatial working memory, that is, when verbal encoding is less efficacious with respect to other strategies. Failing in finding the opposite trend in fDS and bDS, that is, women performing better than men on these tasks, previously documented, may be due to the fact that we selected a sample of young subjects with the same educational level. Indeed, gender differences in verbal working memory have been reported especially for low level of education. Furthermore, our results suggest that such differences are more related to the type of material (verbal vs. visuo-spatial) more than to the type of processing (active vs. passive). This last finding supports the idea that when age and educational level are well matched among sexes, differences due to the stimuli processing disappear. [ABSTRACT FROM AUTHOR]

People orient themselves in the environment using three different, hierarchically organized, spatial cognitive styles: landmark, route, and survey. Landmark style is based on a representation encompassing only visual information (terrain features); route style is based on a representation that connects landmarks and routes using an egocentric (body-centred) frame of reference; survey style is based on a global map-like representation that mainly involves an allocentric (world-centred) frame of reference. This study was aimed at investigating whether individual spatial cognitive style affected the way to plan a path when searching for a lost object. Participants with landmark, route, and survey style were assessed with an ecological navigational planning task (the Key Search Task), which required planning a strategy to search for the lost key in a hypothetical wide squared field. Results showed that spatial cognitive styles were associated to different navigational planning strategies, although the time to complete the Key Search Task was comparable across the styles. As revealed by the Key Search Task score, survey style individuals were the best navigational planners, route style individuals were less efficient and landmark style individuals were the least efficient. These results suggest that spatial cognitive style has effects on navigational planning. Implications for clinical settings, such as for developmental topographical disorientation, are discussed. [ABSTRACT FROM AUTHOR]

• fMRI studies use visual illusions to elicit perceptual inference related networks. • ALE meta-analysis reveals separate networks related to static and motion illusions. • These networks include areas of both ventral and dorsal visual streams. • The LOC is connected to middle temporal, parietal and premotor cortices. • These nodes are involved in perceptual inference, impaired in hallucinations. Visual illusions have long been used to study visual perception and contextual integration. Neuroimaging studies employ illusions to identify the brain regions involved in visual perception and how they interact. We conducted an Activation Likelihood Estimation (ALE) meta-analysis and meta-analytic connectivity modeling on fMRI studies using static and motion illusions to reveal the neural signatures of illusory processing and to investigate the degree to which different areas are commonly recruited in perceptual inference. The resulting networks encompass ventral and dorsal regions, including the inferior and middle occipital cortices bilaterally in both types of illusions. The static and motion illusion networks selectively included the right posterior parietal cortex and the ventral premotor cortex respectively. Overall, these results describe a network of areas crucially involved in perceptual inference relying on feed-back and feed-forward interactions between areas of the ventral and dorsal visual pathways. The same network is proposed to be involved in hallucinogenic symptoms characteristic of schizophrenia and other disorders, with crucial implications in the use of illusions as biomarkers. [ABSTRACT FROM AUTHOR]

Mental imagery plays a crucial role in several cognitive processes, including human navigation. According to the Kosslyn's Model, mental imagery is subserved by three components: generation, inspection and transformation. The role of transformation, where by individuals recognise, from a different perspective, a place they have already visited, is no longer a matter of debate. However, the role of the other two components when recalling a map from different perspectives, has never been fully investigated. In the present study, we enrolled forty-nine college students and asked them to learn a schematic map and to provide directional judgements aligned or counter-aligned compared to the learnt map orientation. Their mental imagery generation, inspection and transformation skills were also investigated. Results demonstrated that all three visual mental imagery components negatively correlate with errors in providing directional judgements. Specifically, generation assumes a role in aligned directional judgements, while inspection and transformation predict the capability to provide counter-aligned directional judgements. Although all mental imagery components play a role in mentally recalling a map, only the proficiency in inspection and mental rotation can predict the accuracy in changing perspective. [ABSTRACT FROM AUTHOR]

In this paper, we analysed the growing penetration of generating units from renewable energy sources in transmission power systems. Among the possible effects of the interaction of distributed generation (DG) with transmission systems, we considered the abnormal operating conditions caused by short circuits in the transmission systems and the resulting voltage sags that occur in the network. A systematic method is presented for analysing the voltage sag behaviour of any transmission system in which large DG units are connected to the transmission system by means of High Voltage/Medium Voltage (HV/MV) stations. The method proposed for obtaining the voltage sags is the fault position method (FPM), from which we derived a graphical visualization of the during-fault voltage (DFV) matrix as a valuable tool to obtain an immediate measure of the propagation of voltage sags in the network. The results obtained were based on a portion of a real transmission system. The system that we considered is an actual portion of the Italian transmission system, and all of the quantities we used were obtained from the data of the Transmission system operator (TSO). [ABSTRACT FROM AUTHOR]

The problem of developing a definition that adequately assesses power-quality (PQ) levels in the presence of distributed generation (DG) is addressed by using proper probabilistic indices for distribution networks. In the planning of new DG installations, these indices take the variation of PQ level into account and use weighting functions properly. They are useful in quantifying the impact of the installation of DG units because they can consider several PQ disturbances simultaneously. Also, they indicate how each PQ disturbance may affect the decision concerning the installation of DG units. Several tests on real distribution networks were performed and discussed in order to show the usefulness of these indices in evidencing the impact of DG on PQ levels. The analysis of the electrical distribution systems on the basis of the considered indices is valuable also to help decide the best allocation and size of distributed generators. [ABSTRACT FROM AUTHOR]

Abstract-Electrical power system robustness is defined as the intrinsic capacity of an electrical power system to maintain assigned disturbance levels when external conditions change. This paper compares two methods for estimating voltage dip severity: the critical distance method and the fault position method. Their differences are not linked to the type of network but to the type of results which we are searching for. This paper proposes a graphical color visualization of the during fault voltage matrices that immediately correlates dip severity with colors defined by a proper scale. New robustness indices are also proposed to synthesize bus performance in terms of affected and exposed areas. Numerical applications refer to real transmission and real distribution systems. [ABSTRACT FROM AUTHOR]

The ac/dc/ac double-stage converter, frequently used nowadays to provide ac adjustable frequency and magnitude voltages in the adjustable-speed drives, consists of a voltage source inverter (VSI) fed by a three-phase diode bridge rectifier; this rectifier generates high line current harmonics in the supply system. This paper presents a complete modelling of the VSI-fed drives, when energized by nonsinusoidal supply voltages, based on the analytical form of the current harmonics injected in the supply system; the equations of the current harmonics are obtained for both the continuous and discontinuous current modes and are derived by Fourier analysis of steady-state current time evolution. The high accuracy of the proposed models is demonstrated by comparison with the results of time-domain simulation. The modelling is useful to study the effects of supply voltage distortions on current harmonics injected in the supply system, both in continuous and discontinuous mode, with a very short computing time. [ABSTRACT FROM AUTHOR]

Examines a method which allows the optimal economic selection of medium-voltage cables in nonsinusoidal operating conditions. Initial investment costs and the Joule losses costs; Adoption of simplified approach by the IEC Standard 1059; Development of numerical applications to medium-voltage cables.

This paper presents the preliminary results of our research activity aimed at forecasting the number of voltage sags in distribution networks. The final goal of the research is to develop proper algorithms that the network operators could use to forecast how many voltage sags will occur at a given site. The availability of four years of measurements at Italian Medium Voltage (MV) networks allowed the statistical analyses of the sample voltage sags without performing model-based simulations of the electric systems in short-circuit conditions. The challenge we faced was to overcome the barrier of the extremely long measurement times that are considered mandatory to obtain a forecast with adequate confidence. The method we have presented uses the random variable time to next event to characterize the statistics of the voltage sags instead of the variable number of sags, which usually is expressed on an annual basis. The choice of this variable allows the use of a large data set, even if only a few years of measurements are available. The statistical characterization of the measured voltage sags by the variable time to next event requires preliminary data-conditioning steps, since the voltage sags that are measured can be divided in two main categories, i.e., rare voltage sags and clusters of voltage sags. Only the rare voltage sags meet the conditions of a Poisson process, and they can be used to forecast the performance that can be expected in the future. However, the clusters do not have the characteristics of memoryless events because they are sequential, time-dependent phenomena the occurrences of which are due to exogenic factors, such as rain, lightning strikes, wind, and other adverse weather conditions. In this paper, we show that filtering the clusters out from all the measured sags is crucial for making successful forecast. In addition, we show that a filter, equal for all of the nodes of the system, represents the origin of the most important critical aspects in the successive steps of the forecasting method. In the paper, we also provide a means of tracking the main problems that are encountered. The initial results encouraged the future development of new efficient techniques of filtering on a site-by-site basis to eliminate the clusters. [ABSTRACT FROM AUTHOR]

This paper deals with the optimal planning of the electrical energy storage systems in the microgrids aimed at cost minimization. The optimization accounts for the compensation of the voltage dips performed by the energy storage systems. A multi-step procedure, at the first step, identifies a set of candidate buses where the installation of a storage device produces the maximum benefit in terms of dip compensation; then, the life cycle costs in correspondence of different alternatives in terms of size and location of the storage systems are evaluated by considering an optimized use of the energy storage systems. The simulations on a medium voltage microgrid allowed validating the effectiveness of the proposed procedure. [ABSTRACT FROM AUTHOR]

This paper presents a probabilistic model for supporting the process of decision making about the value of new lighting systems in existing road tunnels when some data and parameters are affected by uncertainty. The proposed model, which we have called Probabilistic Energy Screening of Tunnel (PrEST), accounts for both the technical performance and the economic objectives of the new lighting systems. The technical performance is described on an adequate (x, y) plane that was defined by two indices. The first index measured the consumption of electricity per kilometre of tunnel lengths; the second index measured the performance of the lighting systems per unit of illuminated area. The economic results were measured by the net present value of the savings and by the payback period. Both the terms account for initial capital investments, energy and maintenance costs. PrEST was applied to two real road tunnels in service in Italy showing that the statistics of the results can support a final decision in function of the business strategy. [ABSTRACT FROM AUTHOR]